The present invention relates to a method for braking a vehicle which is operable by a motor or by muscular power, in particular an electric bicycle. Such a vehicle includes a hydraulic front wheel brake and a hydraulic rear wheel brake, each of which is separately actuatable by a driver. The brake pressure effectuated at the front wheel brake or the rear wheel brake may be changed with the aid of an electrohydraulic brake force influencing device, in that the latter is controlled by an electrical brake pressure control device. The brake pressure at the front wheel brake and/or rear wheel brake, and thus also the brake force, may be increased and/or decreased in this way.
In another aspect, the present invention relates to an electrohydraulic braking device which includes a hydraulic front wheel brake and a hydraulic rear wheel brake, as well as a separate brake actuating device for each of these two brakes. The braking device also includes an electrohydraulic brake force influencing device for increasing and/or decreasing a brake pressure of the front wheel brake and/or a brake pressure of the rear wheel brake, and thus for increasing or decreasing the brake force thereof. In addition, the braking device includes an electrical brake pressure control device, with the aid of which the brake force influencing device is controllable.
Conventional antilock braking systems (ABS systems) for two-wheel and multi-wheel vehicles include wheel sensors via which the movement of a wheel may be detected. Based on these measurements, the ABS system may determine whether or not a wheel is locked during braking, and may thus control the braking operation in such a way that the friction state between the tires and the base surface ranges at the limit between rolling friction and sliding friction. This control is typically carried out for each wheel individually. For this purpose, the brake pressure for the individual wheel brakes is adjusted with the aid of a brake pressure control device.
An ABS system, preferably for a bicycle, is described in German Patent No. DE 10158382 A1, for example.
German Patent Application No. DE 102010049474 A1 describes a hydraulic braking system having an antilock braking function, preferably for motorcycles, mopeds, and vehicles without an independent drive. A hydraulic system including a hydraulic pump is provided which implements the antilock braking function via a hydraulic circuit.
German Patent Application No. DE 102010038525 A1 describes a braking device having active brake force limiting, and a two-wheeled vehicle which includes such a braking device. A piezo stack is integrated into the hydraulic line of the braking device. By activating the piezo stack, it may expand or contract, causing the volume in the line of the braking device to increase or decrease. In this way, the known ABS behavior of a passenger vehicle may be achieved in a bicycle, for example.
In addition, a conventional braking system for motorcycles includes a first of two brake actuating devices acting on the front wheel and also on the rear wheel. The second braking device acts only on the front wheel. The first braking device is designed in such a way that when it is actuated, a brake pressure which is suitable for a typical normal case is directed to the front wheel brake and to the rear wheel brake. The second braking device for the front wheel is intended as an auxiliary brake for emergencies or special driving situations, such as traveling with a pillion rider or traveling on a steep downhill grade, for which an increased brake force on the front wheel is necessary. This system was developed in the 1970s by the Italian motorcycle manufacturer Moto Guzzi, and is a purely hydraulic system.